I agree that the votes he got in the Republican primary is a good sign for Sanders’s crossover appeal (about four times as many as Clinton got, by the way). But as someone who lives in NH and who canvassed for Sanders here, I don’t think it is quite as good a sign as some people are making it out to be. As most people know, NH is an “open primary” state, which means that you don’t have to be a party member to vote in a party’s primary. But I think most people don’t know the mechanics of how it works here: you can only vote in (e.g.) the Democratic Party’s primary if, when you walk into the polls, you are registered as a Democrat or if you are unaffiliated, in which case, on the day of voting, you can switch your registration to Democrat. If you walk into the polls registered as a Republican, you can only vote in the Republican primary. (I think you can switch your affiliation up to two weeks before the primary.) Also, many NH voters strategically switch their party affiliation (switching it back to “unaffiliated” or to the other party after they vote) depending on where they think they can have a meaningful impact. But some people forget to switch their affiliation back. Given all this, I think it’s likely that many of the people who wrote in Sanders (or Clinton) in the Republican primary may have been Democratic-leaning unaffiliated voters, or even people who are “really” Democrats (i.e., that’s where their heart is and they are usually registered as Democrats), but who had forgotten to switch their affiliation back after some previous election. Still, I think it’s true that there’s great crossover appeal for Sanders among Republicans. Evidence: a relative of mine, who is normally a registered Republican and went into the primary intending to vote for Chris Christie, discovered when she walked in that she was still registered as a Democrat from some previous election. So she voted for Bernie. (Don’t ask me how she can support both Christie and Bernie, but I still think it’s a good sign for Bernie that there are people like this out there.)